7-Deaza-2,8-diazaadenine containing oligonucleotides: synthesis, ring opening and base pairing of 7-halogenated nucleosides |
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Authors: | Wenqing Lin |
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Institution: | a Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie, Universität Osnabrück, Barbarastr. 7, 49069 Osnabrück, Germany b Center for Nanotechnology, Gievenbecker Weg 11, 48149 Münster, Germany |
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Abstract: | Oligonucleotides containing 7-bromo-7-deaza-2,8-diaza-2′-deoxyadenosine (3) and 5-amino-3-bromo-4-carbamoyl-1-(2′-deoxy-β-d-erythro-pentofuranosyl)pyrazole (4) were synthesized. Compound 3 was prepared from 7-bromo-8-aza-7-deaza-2′-deoxyadenosine (5) via the 1,N6-etheno derivative 6 and was converted into the phosphoramidite 11. The 7-bromo substituent of 3 increases oligonucleotide duplex stability compared to the non-halogenated nucleoside. Oligonucleotides incorporating 3 are transformed to those containing 4 during long time deprotection at elevated temperature (25% aq ammonia, 60 °C, 30 h). Compound 3 forms a strong base pair with dG. The base pair stability decreases in the order dG>dT>dA>dC. Similar recognition selectivity is observed for the pyrazole nucleoside 4, however, due to decreased stacking and higher flexibility of the pyrazole moiety, duplexes are less stable than those containing 3. |
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Keywords: | Oligonucleotides Base pairing Duplex stability Nucleosides Azapurine Pyrazole |
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